The present invention provides improvements in the processing or treatment of grains such as wheat. More particularly, the present invention is directed towards the provision of whole grain flour such as whole wheat with the color and taste comparable to white flour or a “white” whole wheat flour. Also, the present invention provides methods for preparing such improved white whole wheat flour and further to intermediate products useful in the production of such improved finished products as white whole wheat flour. Such intermediate products include, for example, bleached grain kernels such as bleached wheat kernels.
Most consumers have experienced and readily recognize the difference between whole wheat bread and ordinary white bread. Most consumers also know that whole wheat bread is more nutritious, but consume white bread anyway, because they like the taste better. This is especially true of children who can be particularly selective in food choices.
Through a particular treatment process, the present invention is able to lighten the darker color of whole wheat flour, and all but eliminate the bitter flavors. As a result, the present invention provides whole wheat flours that can be used to provide finished whole wheat products that look and taste as good as those made with regular white flour.
The principle species of wheat are Triticum vulgare or bread wheat; T. durum which has extra hard kernels used primarily for macaroni and related pasta products; and T. compactum or club wheat, which has very soft kernels. Numerous varieties and cultivars within each species are known.
All wheat generically comprise a major starchy endosperm, a smaller germ or sprouting section of the seed and a surrounding bran or husk layer. The endosperm makes up about 82–83% of the wheat kernel and is used in the production of flour. Typically, the bran makes up 14–15%, is removed from the kernel and is used in animal and poultry feed. However, the bran can also be milled along with the endosperm to produce whole wheat flour. The germ is usually separated from the rest of the kernel because its fat content limits the shelf life of the flour. The bran with or without the germ is sometimes referred to as “millfeed”. Some special purpose whole grain flours include not only the bran but also the germ fraction.
In the United States, wheat is classified according to whether it is hard or soft, white or red, and planted in winter or spring.
Soft or spring wheat is typically planted in the spring and harvested later in the fall. Soft wheat is normally white wheat. White soft wheat is used for the donut and pastry industries since a white color and bland taste are essential flour quality attributes.
Hard or winter wheat is typically planted in the fall and harvested the following season in mid-summer. Winter wheat is normally red. Hard or red wheat is used for bread production. Red wheat has a distinctive taste due to tannins in the bran. To minimize the amount of these flavor-bearing tannins, the wheat grain is milled so as to have as small a fraction as possible of the bran containing these tannins. Naturally white hard wheat is also increasingly available commercially and being used more and more.
Even though the endosperm fraction is about 83%, in a typical flour milling process, the extraction rate of white patent flour generally runs about 72–75%. That is, for every hundred pounds of wheat, about 72–75 pounds of flour is obtained. This flour contains about 1–2% dietary fiber from small amounts of the bran. The balance millfeed is very low value comprising bran and germ although containing some of the desirable endosperm.
The milling process can be adjusted to obtain an increase in the flour yield but at the cost of including some of the bran. The presence of bran may lower the quality and thus value of the flour more than the increase in the value of the increase in yield. That is, the amount of flour obtained during the milling process is limited by contamination of the flour with bran that deteriorates flour quality. For flour made from red wheat, less bran in the flour can be tolerated due to the presence of more color and flavor tannins in the bran. The darker bran typically makes the flour grayish in color, and also imparts bitter flavors.
The present invention provides a particular chemical lightening treatment or wetting process, or wet bleaching process that bleaches wheat kernels after cleaning but prior to milling. Since wheat is typically wet tempered prior to milling anyway, this process is commercially practical with existing milling systems.
The principle advantage of the present invention is the provision of white whole grain flour having a high fiber content (≈11–12%) and other nutritional advantages of a whole grain flour that nonetheless has a white color and bland flavor comparable to conventional white flour. Since additional endosperm is associated with the bran is also included, the yield of the flour milling process is surprisingly and, dramatically increased. More surprisingly, the amount of flour obtained can be increased without deterioration in flour quality in terms of color and flavor.
Still another benefit is that the present invention provides enzyme inactivation that increases the stability of the flour.
Still another benefit is that the present invention provides substantial reductions in the viability of toxin producing molds and reductions in levels of mycotic toxins in the flours that can occur as a result of mold growth prior to milling.
These and further objects and advantages of the present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings.